Thanks! This is incredibly useful.

One problem, though: When I try to use the insert-xml-char function, Emacs segfaults. Any idea on why?

But entities aren't just useful for inserting characters outside the US-ASCII range. A document might for example contain the version of the software tool it desribes; with entities I simply change one entity declaration and get the new version number in all the fifty places (search and replace could go wrong and confuse version numbers of other tools mentioned). It would be great to have some mechansim for declaring simple constants in XML without having to use DTD doctype declarations with internal subsets.

Tobi: XInclude.

http://www.w3.org/TR/xinclude/

I need to do more work on it, but I've been using a separate step for character entity replacement prior to validation.

http://simonstl.com/projects/ents/

Ents uses an XML file which lists all the names and values of character entities, and I run it as a pre-processor before parsing or just directly on docs at the command line. Defining new entities is pretty simple, and one of the nicer aspects of this is that I can run it backwards to produce the entity-fied version instead of char ref version.

But then, since I don't use Emacs, I have to resort to such hackery, right?

I'm sorry Mike, I can't imagine why it segfaults. Send me your particulars in email and I'll see if I can help.